Electric measuring instrument.



P. HOLDEN.

PATENTED MAY 14, 1907.

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FRANK noLDENjoFLoNDoN, ENGLAND, ASSIGNOR TO GENERAL ELEGTR 13 COMPANY,A" CORPORATION OF NEW YORK.

ELECTRIC MEASURING IN$TRUIVIENT.

To (Li/Z whomit "my concern:-

Be it known that I, FRANK HOLDEN, a citizen of the United States,residing at London,

England, have invented certain new and use- 5 ful Improvements inElectric- Measuring lnstruments, of which the following is aspecification. i

My invention relates to electrical measuringinstruments and particularlyto that type IO of instrument in which the current to be measured (or acertain portion thereof) passes through a conducting liquid contained ina chamber located in a magnetic field, thereby producing a tendency forthe liquid to flow I5 through the chamber, a reservoir being connectedwith one side of it and a gagetube to the opposite side of the chamber.The height to whichthe liquid rises in the gage tube is proportional tothe current passing through the instrument, and an indication of thecurrentvalue may thus be obtained from a scale located adjacent thetube.

An integrating meter operating on this principle is covered by myco-pending ap- 2 plication, Serial No. 297,600, filed Jan. 24th,

In indicating instruments operating on the principle above described,there is no continuous movement of the liquid conduc- 3 tor. That is,there is no circulation of the liquid through a closed path as thereis-in the integrating meter. The current, therefore, is passingconstantly through nearly the same mass of liquid and there is littleopportunity for the heat generated therein to be dispelled. Heating ofthe liquid to any great extent is of course objectionable and thecurrent capacity of indicating instruments of this kind has been limitedfor 4 this reason. The chief object of my invention is to overcome thisdilliculty and for .this purpose 1 construct the apparatus so that acontinuous circulation of the liquid takes place. This endis attained bythe use of aby-pass of small cross section between the tubes which carrythe liquid to and from the chamber located in the magnetic field.

My invention further consists in the improved construction of apparatushereafter described. The details of my invention will be understood fromthe following description when taken in connection with the accompanyingdrawings in which Figure 1 is a front elevation of an instru- Specificatiozi of Letters Patent. Application filed December 14,1906.Serial No. 347,829.

Patented May 14, 1901 ment embodying my invention Fig. 2 is a side;elevation thereof; Fig. 3 is a perspective View in a somewhatdiagrammatic form of the chamber which is located in the magnetic fieldand the parts adjacent. thereto and Fig. 4 is an elevation/of am'odilied form.

of tube and reservoir.

.The various parts of the instrument maybe supported in any suitablemanner, as by being attached to a back 1.

4 havingthe projection 5 upon which the magnet is supported. The ends ofthis magnet are embedded in a pair of rectangular blocks 6 and 7 made ofinsulating material, such as slate. These blocks have embedded thereinpole pieces 8' and 9; these pole pieces being so arranged that when theblocks are superposed the pole faces confront each other. These polepieces are attacher. to the ends of the magnet, and being of reducedcross section'a veryintense magnetic A magnet 21 may be held as by thescrew 3 and the block field set up between the adjacent pole laces. I

In order to form the space for the conducting liquid,v this beingusually.mercury, a sheet 10 of mica or other suitable material, in thecenter of which is cut an-opening or channel 11 of cruciform shape, isinterposed between the blocks 6 and 7. The mica sheet is so located thatthe central portion of the crwiform opening is wholly within the area ofthe polelaces, and the limbs of saido'pening are parallel to the sidesof the blocks. The ends of two opposite limbs are connected by openings12 and 13 with the tubes 1-1 and 15 which are sealed into the sides ofthe blocks. The ends of the other two limbs of the cruciform opening inthe mica sheet have extending into them conductors 16 and 17 which aresealed into the blocks. This construction is clearly shown in Fig'.Iland is the same as that described in my co-pending apreservoir 1%) fora purpose hereafter e2;-

plained.

Connected with the passages 12 and'1'3 is r the tube 22 which is of verysmall bore as compared with the bore of the tubes 14 and 0f the mercuryto keep the same cool without,

'15. This tube 22 serves as a hy-p-ass around the chamber in the micasheet between the i slate blocks and permits enough circulation j Whencurrent. is passed through the instrument a pumping action is set up inthe chamber within the blocks and the mercury is j caused to rise in thegage tuhe being at the same time drawn from the reservoir. The I mercurycontinues to rise in the gage tube 20 until-the hydrostatic pressure,due to the difference of level of the mercury in the reservoir and themercury in the gage tulic. halances the pressure exerted hy the pumpingaction in the cruciform chamhcr. By hav ing the upper end of the gagetu'he henl over and projecting intothe rcst-a'voir. any mcrcury that mayhe driven up to the top of the tuhe hy a sudden great increase ofcurrent will flow over into the reservoir.

'lhe'instrunu-nt may he adapted for usc as a maximum demand indicator hyproviding'i 4 understood from the foregoing description. I

the tube 20 with a check valve or with a. nonreturn lloat which will hedriven up in the tube as the mercury riscs Fig. 4 shows a 1 modifiedform of reservoir which consists of a hull) 26 hlown in a part of thctuhe .27 I which serves as the gage tuhe of the instrument. in order toprevent air huhhlcs from being caught in the mercury a wire or glassfilament 2h may he placed in the tuhc 27 with its cnds dipping into themercury in the reservoir and the mercuryin the gage t'ihc. With thisconstruction the apparatus may he hermetically scaled or, if desired,mayhc exhausted of air. Instead of the pcrnmncnt magnet 2 anclectro-magnet mayol course he used. Other mmlilications will occur tothose skilled in the art. and l. wish it undcrstood that it is myintention to inch'de all such as hei'ng within the scupc oi'niyinyention asdclincd in thcclaimsappended liciclo.

My device may he used as an annnctcr hy connecting it across a lowrcsistancc shunt interposed in the circuit. the current in which it isto he measured or it may he used as a voltmeter hy arranging aresistance in series with it and connccting to the points 'in thecircuit hctwecn which thc dill'crcncc ol' potcntial is to he mcasurcd.

What *i claim as new and dcsirc to secure hy liettcrs Patcnt ol' thclnilcd States. isr

l. An clcctricai measuring instrument comprising means for producingaonagnhtic field, a chamber containing a liquid locatedl in said fielthasupply tuhe and a gage tulc connected to said chamher, conductors enlteringsaid chamber, and a hy-pass around i said chamber for permittingcirculation "of said liquid.

2. An electrical measuring instrument comprising means tor producing amagnetic field, a chamber containing a. conducting liquid located insaid field, a supply tuhe con-- nccted to one side oi said chamber and agage tuhe connected to the opposite side, conductors entering saidchamber and arranged so that a currcnt passing from one to the otherthrough the liquid will traverse the magneticfield. and a hypass aroundsaid chamhcr for permitting circulation of said liquid.

3. An electrical measuring instrument comprising means for producing amagneticfield, a c'hamhcr containing a liquid located in said lield, areservoir. a tuhc connecting the reservoir and chamhcr; a. gage tuhcrising from said chamher, conductors entering said chaml er. and ahy-pass around said chamhcr for permitting circulation of said liquid.

4. An electrical measuring instrument comprising means l'or producing-:rlnagnctic field, a narrow chamher containing mercury located in saidlicld. a reservoir. a tuhe connccting the reservoir and chamhcr, a gagetuhe rising from said chamhcr. conductors cutering said chanihcr. and ahy-pass of small horc around said chamhcr for permitting circulation ofsaid mercury.

An clcctricnl measuring instrument comprising means for producing amagnetic held. a chamhcr containing mercury located in said field, areservoir. a tuhc connecting the bottom oisaid reservoir and thcclunnhcr. a

. gage tuhc rising from said chamhcr and connected to the top of thereservoir. conductors cntcring said chamhcr, and a hy-pass around saidchamhcr for permitting circulation of said liquid. t

o. .\n clcclricul nn-asuring instrument comprising hlocks of insulatingmaterial, a sheet ol non-cmnllu-ting material having a channel thereinlocalcd hctwccn said hlo'clcs, a magnet having its poles cxtcndi'ngthrough said l)l()(l\'s close to said channel, conductors extending tosaid channel. a supply tuhc conncctcd to one side of said channel, agage tulrc onnected to theothcr side of said channel. andfii'hy-passaround said channel for permitting circulation of the mercury con'-taincd in the instrunfcnt.

In witness nhcrcol'. l have hereunto set my hand 'this lst 'lay ofllcccmhcr, ltltlli.

FRANK UWLIHQX. xvii-11055051 i ll. l). Janicsox.

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